Devices for gas cooling plasma arc torches and related systems and methods

ABSTRACT

In some aspects, nozzles for a gas-cooled plasma torches can include a hollow generally cylindrical body having a first end and a second end that define a longitudinal axis, the second end of the body defining a nozzle exit orifice; a gas channel formed in the first end between an interior wall and an exterior wall of the cylindrical body, the gas channel directing a gas flow circumferentially about at least a portion of the body; an inlet passage formed substantially through a radial surface of the exterior wall and fluidly connected to the gas channel; and an outlet passage at least substantially aligned with the longitudinal axis and fluidly connected to the gas channel.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/858,235 filed Jul. 25, 2013, entitled “PlasmaArc Torch Nozzles, Shields and Retaining Caps,” the contents of whichare hereby incorporated herein by reference in their entirety.

TECHNICAL FIELD

This disclosure relates generally to thermal cutting torches (e.g.,plasma arc torches), and more specifically to devices for gas coolingplasma arc torches and to related systems and methods.

BACKGROUND

Basic components of modern conventional plasma arc torches include atorch body, an electrode (e.g., cathode) mounted within the body, anozzle (e.g., anode) with a central orifice that can produce a pilot arcto the electrode to initiate a plasma arc in a flow of a suitable gas(e.g. air, nitrogen or oxygen) and associated electrical connections andpassages for cooling, and arc control fluids. Generation of the pilotarc may be by means of a high frequency, high voltage signal coupled toa DC power supply and the plasma arc torch, or any of a variety ofcontact starting methods. In some configurations, a shield is mounted tothe torch body to prevent metal that is spattered from the workpiece(sometimes referred to as slag) during processing from accumulating ontorch parts (e.g., the nozzle or the electrode). Generally, the shieldincludes a shield exit portion (also called a shield orifice) thatpermits the plasma jet to pass therethrough. The shield can be mountedco-axially with respect to the nozzle such that the plasma exit portionis aligned with the shield exit portion.

Cooling capacity has been a limitation of previous designs relating toplasma arc torches. For example, previous designs have required the useof cooling mediums other than or in addition to a gas (e.g., coolingwater or liquid) for torches that operate at high (e.g., 100 or 200Amps, or more) current levels. Most of these cooling methods can requirecooling systems external to the torch (e.g., which can include watersupplies, reservoirs, heat exchange equipment, supply pumps, etc.).External cooling systems can increase the associated equipment expense,can require more maintenance, be vulnerable to spills, and in somecases, can require disposal of the cooling medium. The issue of coolingthe plasma arc torch is more acute for higher current systems, as highercurrent systems can generate more heat and have larger cooling demands.Indeed, commercially available plasma arc torch cutting systemsoperating at more than about 100 amperes typically utilize coolingsystems using a liquid coolant (e.g., water or glycol). However, othersystems are possible.

SUMMARY

In some aspects, a nozzle for a gas-cooled plasma arc torch can includea hollow generally cylindrical body having a first end and a second endthat define a longitudinal axis, the second end of the body defining anozzle exit orifice; a gas channel formed in the first end between aninterior wall and an exterior wall of the cylindrical body, the gaschannel directing a gas flow circumferentially about at least a portionof the body; an inlet passage formed substantially through a radialsurface of the exterior wall and fluidly connected to the gas channel;and an outlet passage at least substantially aligned with thelongitudinal axis and fluidly connected to the gas channel.

Embodiments can include one or more of the following features.

In some embodiments, the inlet passage can include an inlet port formedthrough a radial surface of the body. In some cases, the outlet passagecan include an outlet port formed through a second exterior radialsurface of the body between the second end of the nozzle and the inletport.

In some embodiments, the nozzle includes a plurality of (e.g., multiple)inlet passages. In some cases, a radial angle between respective inletpassages is about 120 degrees. In some embodiments, the nozzle includesa plurality of outlet passages. In some cases, a radial angle betweenrespective outlet passages is about 120 degrees. In some embodiments,the nozzle includes a plurality of inlet passages and a plurality ofoutlet passages. In some cases, the inlet passages are radially offsetfrom the outlet passages.

In some embodiments, the circumferential gas flow along the gas channelextends about an entire circumference of the nozzle.

In some embodiments, a portion of the nozzle walls are configured tomate with an exterior surface of a swirl ring. In some cases, the swirlring forms a portion of the gas channel.

In some aspects, a nozzle for a gas-cooled plasma arc torch can includea hollow generally cylindrical body having a first end and a second endthat define a longitudinal axis, the second end of the body defining anozzle exit orifice; a plenum region defined within the body anddirecting a plasma gas; a cooling gas channel formed in the first endbetween an interior wall and an exterior wall of the cylindrical body,the cooling gas channel isolating a cooling gas from the plasma gas; asubstantially radially oriented inlet passage fluidly connected to thegas channel; and a substantially longitudinally oriented outlet passagefluidly connected to the gas channel.

Embodiments can include one or more of the following features.

In some embodiments, the radially oriented inlet passage also includesan inlet port formed through a radial surface of the body. In someembodiments, the longitudinally oriented outlet passages also include anoutlet port formed through a radial surface of the body between thesecond end of the nozzle and the inlet port. In some embodiments, thenozzle includes a plurality of radially oriented inlet passages. In somecases, a radial angle between respective inlet passages is about 120degrees. In some embodiments, the nozzle also includes a plurality ofoutlet passages. In some cases, a radial angle between respective outletpassages is about 120 degrees. In some embodiments, the nozzle includesa plurality of inlet passages and a plurality of outlet passages. Insome cases, the inlet passages are radially offset from the outletpassages.

In some embodiments, the circumferential gas flow along the gas channelextends about an entire circumference of the nozzle. In someembodiments, a portion of the nozzle walls are configured to mate withan exterior surface of a swirl ring. For example, the swirl ring canform a portion of the gas channel.

In some embodiments, the plasma gas and the cooling gas combine at theexit orifice of the nozzle.

In some aspects, a method for cooling a nozzle for a plasma arc torchcan include providing the nozzle having a hollow body with a first endand a second end, the second end of the body defining a nozzle exitorifice, a gas channel formed in the first end of the body, asubstantially radially oriented inlet passage fluidly connected to thegas channel, and a substantially longitudinally oriented outlet passagefluidly connected to the gas channel; flowing the cooling gas throughthe inlet passage into the gas channel; directing the cooling gas alongthe gas channel; and discharging the cooling gas from the gas channel tothe outlet passage.

In some aspects, a nozzle for a gas-cooled plasma arc torch can includea body having a first end and a second end that define a longitudinalaxis; a plenum region substantially formed within the body, the plenumregion extending from the first end of the body and configured toreceive a plasma gas flow; an exit orifice located at the second end ofthe body and oriented substantially coaxially with the longitudinalaxis, the exit orifice fluidly connected to the plenum region; and afeature on an outer surface of the body configured to increase coolingby receiving a cooling gas flow flowing at high velocity generally in adirection of the longitudinal axis along a length of the body, animpingement surface of the feature configured to receive the cooling gasflow at a substantially perpendicular direction relative to theimpingement surface and to redirect the cooling gas flow to promotecooling and uniform shield flow.

Embodiments can include one or more of the following features.

In some embodiments, the feature is disposed about a circumference ofthe outer surface of the nozzle body.

In some embodiments, the substantially perpendicular direction can bebetween about 45 degrees and 90 degrees relative to the impingementsurface.

In some embodiments, a cross section of the impingement surface of thefeature includes a substantially planar surface that is arrangedsubstantially perpendicularly to the cooling gas flow. In someembodiments, the impingement surface of the feature includes asubstantially conical surface. In some embodiments, the feature ispositioned on the nozzle adjacent a corresponding feature of a shieldcomponent. In some cases, the corresponding feature is a mixing chamber.

In some embodiments, the high velocity is at least 300 meters persecond.

In some embodiments, the feature includes at least a portion of achamber of sufficient size to increase a flow uniformity of the coolinggas by performing as a buffering chamber to reduce cooling gas flowtransients. In some cases, the chamber extends about a circumference ofthe outer surface of the nozzle.

In some embodiments, the nozzle includes a sharp corner adjacent theimpingement surface to generate turbulence in the cooling gas flow.

In some aspects, a nozzle cooling system for a plasma arc torch caninclude a nozzle having a body with a first end and a second end thatdefine a longitudinal axis, a plenum region substantially formed withinthe body, the plenum region extending from the first end of the body andconfigured to receive a plasma gas flow, an exit orifice located at thesecond end of the body and oriented substantially coaxially with thelongitudinal axis, the exit orifice fluidly connected to the plenumregion, and a feature on an outer surface of the body configured toincrease cooling by receiving a cooling gas flow flowing at highvelocity generally in a direction of the longitudinal axis along alength of the body, an impingement surface of the feature configured toreceive the cooling gas flow at a substantially perpendicular directionrelative to the impingement surface and to redirect the cooling gas flowto promote cooling and uniform shield flow; and a nozzle retaining capcomprising a generally cylindrical body and a securing flange, thesecuring flange of the retaining cap including a plurality of shield gassupply ports angled generally along the longitudinal axis of the nozzleat an angle that is substantially perpendicular to the impingementsurface of the feature of the nozzle.

Embodiments can include one or more of the following features.

In some embodiments, the nozzle retaining cap can include about 10shield gas supply ports.

In some aspects, a nozzle-shield cooling system can include a nozzlehaving a body with a first end and a second end that define alongitudinal axis; a plenum region substantially formed within the body,the plenum region extending from the first end of the body andconfigured to receive a plasma gas flow; an exit orifice located at thesecond end of the body and oriented substantially coaxially with thelongitudinal axis, the exit orifice fluidly connected to the plenumregion; and a feature on an outer surface of the body configured toincrease cooling by receiving a cooling gas flow flowing at highvelocity generally in a direction of the longitudinal axis along alength of the body, an impingement surface of the feature configured toreceive the cooling gas flow at a substantially perpendicular directionrelative to the impingement surface and to redirect the cooling gas flowto promote cooling and uniform shield flow; and a shield for the plasmaarc torch including a generally conical body and an end face having ashield exit orifice, an interior surface of the shield defining a mixingchamber at a location corresponding to the impingement feature of thenozzle when assembled together, the mixing chamber having an inlet edgepositioned to direct the cooling gas from the impingement feature intothe mixing chamber.

Embodiments can include one or more of the following features.

In some embodiments, the mixing chamber and inlet edge extend about acircumference of the interior surface of the shield. In someembodiments, a profile of the inlet edge is an acute angle. In someembodiments, the inlet edge extends toward the first end of the nozzlebody. The inlet edge can also extend toward the second end of the nozzlebody.

In some embodiments, the shield has at least two inlet edge features.

In some embodiments, the mixing chamber has a bulbous cross section. Insome embodiments, the mixing chamber is of sufficient volume to increasea flow uniformity of the cooling gas by performing as a bufferingchamber to reduce cooling gas flow transients.

In some aspects, a shield for an air-cooled plasma arc torch can includea body having a proximal end configured to mate with a torch body of theplasma arc torch and a distal end; an exit orifice formed in the distalend of the body; and an interior of the shield defining a shield flowsurface that forms a portion of a shield gas flow channel, the shieldgas flow channel directing a flow of shield gas along the interiorshield flow surface in a flow direction from the proximal end to theexit orifice at the distal end of the body, the interior of the shieldalso defining a flow feature disposed on the interior shield flowsurface, the flow feature formed circumferentially about an interior ofthe body between the proximal end and the exit orifice, the flow featureconfigured to reverse the flow direction of the shield gas flow withinthe shield gas flow channel.

Embodiments can include one or more of the following features.

In some embodiments, the interior shield flow surface includes a mixingchamber formed circumferentially about the body at a portion of theshield gas flow channel adjacent an impingement feature of acorresponding nozzle, the mixing chamber includes an inlet edgepositioned to direct the shield gas into the mixing chamber. In somecases, the flow feature also defines a recombination region, therecombination region between the exit orifice and the mixing chamber.

In some embodiments, the flow feature defines a recombination region,the recombination region between a set of shield vent ports and the exitorifice.

In some embodiments, the flow feature can include a protuberance and arecess that cooperate to reverse the flow direction. In some cases, theprotuberance is adjacent the recess. In some embodiments, the flowfeature includes a protuberance, such that the protuberance is a ridgethat extends around a circumference of the interior shield flow surface.In some embodiments, the flow feature includes a recess, such that therecess is a groove that extends around a circumference of the interiorshield flow surface. In some cases, the flow feature includes aprotuberance, such that the protuberance is between the recess and theexit orifice. The flow feature can be disposed on a conical portion ofthe shield body. The flow feature can be disposed on an end face of thedistal end of the shield body. The flow feature can include aprotuberance, such that the protuberance is disposed at a location onthe interior shield flow surface that corresponds to a complementaryfeature of an adjacent torch nozzle when the shield is attached to theplasma arc torch. For example, the complementary feature of the nozzlecan be a ridge.

In some embodiments, when assembled, a cross section of the protuberanceand the complementary feature of the nozzle can both be parallel to alongitudinal axis of a torch body of the plasma arc torch. In someembodiments, the protuberance and the complementary feature of thenozzle form a tortured flow path.

In some aspects, a nozzle for an air-cooled plasma arc torch can includea body having a proximal end configured to mate with a torch body of theplasma arc torch and a distal end; an orifice formed in the distal endof the body; and an exterior of the nozzle comprising a nozzle flowsurface that forms a portion of a shield gas flow channel, the shieldgas flow channel directing a flow of shield gas along the exteriornozzle flow surface in a flow direction from the proximal end to theorifice at the distal end of the body, the exterior of the nozzle alsohaving a flow feature disposed on the exterior nozzle flow surface, theflow feature formed circumferentially about an exterior of the bodybetween the proximal end and the orifice, the flow feature configured toreverse the flow direction of the shield gas flow within the shield gasflow channel.

Embodiments can include one or more of the following features.

In some embodiments, the nozzle includes a feature on the exteriornozzle flow surface of the nozzle body configured to increase cooling ofthe body by receiving at least a portion of the shield gas flow flowingat high velocity generally in a direction of a longitudinal axis of thenozzle body and along a length of the body, an impingement surface ofthe feature configured to receive the at least a portion of the coolinggas flow at a substantially perpendicular direction relative to theimpingement surface and to redirect the cooling gas flow to promotecooling and uniform shield flow.

In some embodiments, the exterior nozzle flow surface includes a mixingchamber formed circumferentially about the body at a portion of theshield gas flow channel that is adjacent the impingement feature.

In some embodiments, the flow feature can include a protuberance and arecess that cooperate to reverse the flow direction. In some cases, theprotuberance is adjacent the recess. In some embodiments, the flowfeature includes a protuberance, such that the protuberance is a ridgethat extends around a circumference of the exterior nozzle flow surface.

In some embodiments, the flow feature can include a recess, such thatthe recess is a groove that extends around a circumference of theexterior nozzle flow surface. In some embodiments, the flow feature caninclude a protuberance, such that the protuberance is between the recessand the orifice. The flow feature can be disposed on a conical portionof the nozzle body. The flow feature can be disposed on an end face ofthe distal end of the nozzle body. In some embodiments, the flow featurecan include a protuberance, such that the protuberance is disposed at alocation on the exterior nozzle flow surface that corresponds to acomplementary feature of an adjacent torch shield when the nozzle isattached to the plasma arc torch. In some cases, the complementaryfeature of the shield can be a ridge.

In some aspects, a consumable set for an air-cooled plasma arc torchsystem can include a shield including a shield body having a proximalend configured to mate with a torch body of the plasma arc torch and adistal end; an exit orifice formed in the distal end of the body; and aninterior of the shield having a shield flow surface that forms a portionof a shield gas flow channel, the shield gas flow channel directing aflow of shield gas along the interior shield flow surface in a flowdirection from the proximal end to the exit orifice at the distal end ofthe body, the interior of the shield also having a flow feature disposedon the interior shield flow surface, the flow feature formedcircumferentially about an interior of the body between the proximal endand the exit orifice, the flow feature configured to reverse the flowdirection of the shield gas flow within the shield gas flow channel; anda nozzle formed of an electrically conductive material including anozzle body having a first end and a second end that define alongitudinal axis; a plenum region substantially formed within thenozzle body, the plenum region extending from the first end of thenozzle body and configured to receive a plasma gas flow, the plenumregion fluidly connected to the exit orifice; a feature on an outersurface of the nozzle body configured to increase nozzle cooling byreceiving a cooling gas flow flowing at high velocity generally in adirection of the longitudinal axis along a length of the nozzle body, animpingement surface of the feature configured to receive at least aportion of the cooling gas flow at a substantially perpendiculardirection relative to the impingement surface and to redirect thecooling gas flow to promote cooling and uniform shield flow, such thatat least a portion of the cooling gas flow from the impingement surfaceexits the torch at the orifice.

Embodiments can include one or more of the following features.

In some embodiments, the interior shield flow surface further caninclude a mixing chamber formed circumferentially about the shield bodyat a portion of the shield gas flow channel adjacent the impingementfeature.

In some aspects, a method for cooling a nozzle of an air-cooled plasmaarc torch can include supplying a shield gas at a substantiallyperpendicular angle to an exterior feature of the nozzle; redirectingthe shield gas from the exterior feature of the nozzle to a mixingchamber adjacent the feature; and flowing the shield gas from the mixingchamber along a shield gas flow channel to an exit orifice of theshield, the shield gas flow channel at least partially defined by anexterior surface of the nozzle.

Embodiments can include one or more of the following features.

In some embodiments, the method can also include flowing the shield gasfrom the mixing chamber through a recombination region disposed betweenthe nozzle and the shield to produce a substantially uniform shield gasflow at the exit orifice, the recombination region comprising at leastone flow-redirecting member. In some cases, the recombination region canbe downstream of the mixing chamber and include a baffle on an interiorsurface of the shield and a baffle on an exterior surface of the nozzle.In some cases, the shield baffle and the nozzle baffle are adjacent eachother when the shield and the nozzle are assembled to the torch.

In some embodiments, at least a portion of the mixing chamber can bedisposed on the exterior surface of the nozzle. In some embodiments, atleast a portion of the mixing chamber can be disposed on an interiorsurface of an adjacent shield. In some embodiments, at least a portionof the mixing chamber can be disposed on the exterior surface of thenozzle and at least a portion of the mixing chamber can be disposed onan interior surface of an adjacent shield.

In some aspects, a method for providing a uniform shield gas flow for anair-cooled plasma arc torch can include supplying a shield gas to ashield gas flow channel defined by an exterior surface of a nozzle andan interior surface of a shield; flowing the shield gas along the shieldgas flow channel; reversing the flow of the shield gas along the shieldgas flow channel using a recombination region, the recombination regioncomprising at least one flow reversing member; and flowing the shieldgas from the mixing region to an exit orifice of the shield, therebyproducing a substantially uniform shield gas flow at the exit orifice.

In some aspects, a nozzle for a gas-cooled plasma arc torch can includea nozzle body having a proximal end and a distal end that define anozzle body length and a longitudinal axis, the body including; an exitorifice defined by the distal end of the nozzle body; a plenum withinthe nozzle body, the plenum extending from the proximal end of thenozzle body to a plenum floor, a distance from the plenum floor to thedistal end defining a plenum floor thickness, and a distance from theplenum floor to the proximal end of the nozzle body defining a proximalend height; and a bore extending from the plenum floor to the exitorifice, the bore having a bore length and a bore width, wherein thenozzle body has a nozzle width in a direction transverse to thelongitudinal axis, wherein the nozzle body length is greater than thenozzle width, and wherein a ratio of the proximal end height to theplenum floor thickness is less than 2.0.

Embodiments can include one or more of the following features.

In some embodiments, the nozzle can also include a body flange at theproximal end of the nozzle body, an overall length of the nozzle definedby a distance from a proximal end of the nozzle body flange to an endface at the distal end of the nozzle, such that the overall length ofthe nozzle is greater than the nozzle body length. In some cases, thebody flange extends about 0.05 to about 0.5 inches above the nozzleplenum. In some cases, the proximal end height includes the body flange.

The length of the bore corresponds to the plenum floor thickness. Thebore can include a chamfer or a counter bore. The width of the bore canvary along its length. The bore can have a chamfer or a counter bore ateach end of its length.

In some embodiments, the exit orifice can be at an end face of thenozzle.

In some embodiments, a ratio of the length of the bore to the nozzlebody length can be greater than about 0.32.

In some embodiments, a side wall thickness of the plenum can be betweenan inside diameter of the plenum and an outer diameter of the plenum,and the ratio of the plenum side wall thickness to the width of thenozzle body can be about 0.15 to about 0.19. In some embodiments, a sidewall of the plenum can include one or more cooling gas passages.

In some embodiments, the nozzle can be sized to operate in the plasmaarc torch at a current flow of at least 100 amps. In some embodiments,the nozzle can operate at a current to nozzle body length ratio ofgreater than 170 amps per inch.

In some embodiments, the ratio of the proximal end height to the plenumfloor thickness can be less than about 1.4.

In some aspects, a nozzle for an air-cooled plasma arc torch configuredto operate above 100 amps can include a nozzle body having a distalportion defining a conduit substantially aligned with a longitudinalaxis of the nozzle body, the conduit having a conduit length and shapedto direct a plasma gas flow; and a proximal portion coupled to thedistal portion and having a proximal portion length, the proximalportion defining a plenum fluidly connected to the conduit, wherein aratio of a length of the proximal portion to the conduit length can beless than about 2.0, and wherein the nozzle can be configured to permitoperation at a current to nozzle body length ratio of greater than about170 amps/inch.

Embodiments can include one or more of the following features.

In some embodiments, the nozzle can include a body flange at a proximalend of the proximal portion of the nozzle body, an overall length of thenozzle defined by a distance from a proximal end of the nozzle bodyflange to an end face at the distal end of the nozzle, such that theoverall length of the nozzle is greater the nozzle body length. In someembodiments, the body flange of the nozzle can include a flow channel.

In some embodiments, the conduit length can correspond to a plenum floorthickness. In some embodiments, the conduit can include a chamfer or acounter bore. In some embodiments, a width of the conduit can vary alongthe conduit length. In some embodiments, the conduit can have a chamferor a counter bore at each end of its length.

In some embodiments, a side wall thickness of the plenum can be betweenan inside diameter of the plenum and an outer diameter of the plenum,and the ratio of the plenum side wall thickness to the width of thenozzle body can be about 0.15 to about 0.19. In some embodiments, a sidewall of the plenum can include one or more cooling gas passages.

In some embodiments, the cooling gas passages can be sized to permit thenozzle to operate in the plasma arc torch at a current flow of at least100 amps. In some embodiments, the cooling gas passages can be sized topermit operation of the nozzle at a current to nozzle body length ratioof greater than 170 amps per inch.

In some embodiments, the ratio of the length of the proximal portion tothe conduit length can be less than about 1.4.

Embodiments described herein can have one or more of the followingadvantages.

In some aspects, consumable components (e.g., nozzles) as describedherein having a gas cooling channel formed between an inner (e.g.,interior) wall and an outer (e.g., exterior) wall can have greatercooling capabilities than some other consumable components that do nothave similar gas channels. The increased cooling capabilities result inpart because additional cooling gas contact surface area is createdwithin the nozzle through which heat can transfer and be carried away bythe cooling gas. Increased cooling capabilities can result in bettercutting performance, for example, by helping to create more stableplasma arcs and longer usable consumable life. Longer usable consumablelife can lead to fewer consumable replacements needed, which can resultin reduced costs and system downtime.

Further, forming the gas cooling channel within an outer wall of thenozzle can provide for better separation (e.g., isolation) of the gascooling channel from the plasma gas flow path, which can result inincreased cooling capabilities without substantially interfering withdelivery and/or control of the plasma gas.

Additionally, gas cooling channels having one or more horizontal (i.e.,substantially perpendicular to a longitudinal axis of the nozzle) inletsand one or more vertical (i.e., substantially longitudinally) outletswhich may be circumferentially offset from the horizontal inlets, canhelp to provide impinging gas flows onto different surfaces of thenozzle. The impinging flow can help to create turbulent flows foradditional increased cooling.

In some aspects, nozzles described herein having a feature arrangedalong its outer surface that defines an impingement surface to receive acooling gas flow (e.g., a high speed cooling gas flow) can haveincreased nozzle cooling capabilities relative to some otherconventional nozzles. As discussed herein, the impingement surface canbe angled relative to one or more other outer surfaces of the nozzle sothat the cooling gas flow contacts (i.e., impinges) the impingementsurface substantially perpendicularly relative to the impingementsurface, which can result in increased cooling capabilities. Forexample, as discussed herein, the angled impingement surface istypically angled to be arranged substantially perpendicularly to anangled cooling gas flow channel defined within a nozzle retaining capthat provides a cooling gas flow.

Further, the arrangement of the angled impingement surface within amixing channel can help to generate high velocity gas flow mixing, forexample, in part due to the substantially perpendicular impingement ofthe gas flow onto the impingement surface, which can increase coolingcapabilities relative to some other conventional nozzles without suchfeatures. In some cases, the feature and the impingement surface help tocreate a turbulent flow within the mixing channel which further aidscooling. Additionally, in some cases, the mixing channel can help to mixand distribute (e.g., evenly distribute) the flow of the cooling shieldgas around the nozzle so that it can be delivered more evenly. Moreevenly delivered shield gas can create a more stable plasma arc, whichcan result in improved cut speed and consistency.

In some aspects, alternatively or additionally, features of the nozzlecan work in combination with corresponding features (e.g., grooves orflanges) formed on other consumable components, such as a shield, toalter (e.g., disturb, perturb, and/or partially block, redirect, orredistribute) the flow of shield gas flowing between the nozzle and theshield. For example, as discussed herein, some nozzles can include arecess in which a flange of a shield can be partially disposed duringuse. The configuration of the flange disposed within a recess can causethe flowing shield gas to be temporarily redirected (e.g., directed awayfrom and then back towards) the distal end of the torch. Suchredirection can help to mix and distribute the shield gas flow annularlyaround the shield exit orifice so that the distribution of shield gasexiting the torch can be more evenly distributed than in some otherconventional torch systems. More evenly distributed shield gas can beuseful in helping to create a more stable plasma arc by reducing orlimiting inconsistently varying gas flows around the plasma arc.Similarly, other features described herein, such as the complementarymixing channel formed by features and surfaces of the nozzle and/orshield (discussed below with reference to FIG. 3) can also help toreceive gas flow delivered from multiple discrete channels anddistribute the gas flow circumferentially around the nozzle to helpcreate a more evenly distributed gas flow and a more uniform plasma arc.

In some aspects, nozzles as described herein that are designed,proportioned, and constructed to be shorter (i.e., longitudinallyshorter proximal end height), wider (i.e., having a thicker nozzle tip(e.g., a wider or larger end face) and/or thicker plenum side walls),and/or have a longer bore (i.e., a thicker distal region) can producegreater cooling effects relative to some other conventional nozzles thatlack such modified features. In some cases, it is expected that theseproportions result in a nozzle having increased tip mass concentrated atthe distal region (e.g., increased tip mass to volume ratios relative tothe rest of the nozzle), which can result in increased cooling capacity.In particular, increased material mass and volume located at the distaltip of the nozzle, especially increased material positioned radiallysurrounding the exit orifice can provide greater heat transfer pathsthrough which heat can travel outwardly within the nozzle and proximallyaway from the torch tip.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of an example plasma arc torch definingvarious gas flow channels used to deliver shield or cooling gas to thetorch tip.

FIG. 2 is a sectioned view of an example nozzle for a plasma arc torchthat includes a gas channel defined between an interior wall and anexterior wall for directing gas flow circumferentially around the bodyof the nozzle.

FIG. 3 is a cross sectional view of a plasma arc torch having a nozzlecooling system and a flow distribution system defined by features andelements formed along its nozzle and shield.

FIG. 4 is an enlarged cross sectional view of the nozzle cooling systemof FIG. 3 illustrating an example cooling gas flow within and around thenozzle.

FIG. 5 is an enlarged cross sectional view of the flow distributionsystem of FIG. 3 illustrating features formed along the nozzle andshield to redirect and substantially uniformly distribute the shield gasflow annularly around the nozzle.

FIG. 5A is an enlarged cross sectional view of another example flowdistribution system illustrating features formed along the nozzle andshield to redirect and substantially uniformly distribute the shield gasflow annularly around the nozzle.

FIG. 6 is a cross sectional view of an example nozzle for a plasma arctorch having a wider end face and distal end region to distribute heatand increase nozzle cooling.

FIG. 7 is a simulated gas flow model depicting gas flow into and out ofthe gas channel of FIG. 2.

DETAILED DESCRIPTION

In some aspects, consumable components, such as nozzles, can include gascooling channels formed between an inner (e.g., interior) wall and anouter (e.g., exterior) wall, which can provide greater coolingcapabilities than some other consumable components that do not havesimilar gas channels.

FIG. 1 illustrates an example plasma torch 50 that can be used with thevarious aspects and embodiments of the plasma arc torch cooling systems,devices, and methods described herein. Referring to FIG. 1, the plasmatorch 50 can include an electrode 60, a nozzle 100, and a shield 150.The torch 50 can be in electrical communication (e.g., using acurrent-carrying cable (not shown)) with a power supply (not shown) andreceive electrical current from the power supply. The electrical currentreceived from the power supply is transferred, through a current path,to the electrode 60 toward the nozzle 100.

During use, gas (e.g., plasma gas) is directed into a plenum region 80defined between the electrode 60 and the nozzle 100. The plasma gas canbe accelerated (e.g., the plasma gas can be heated, which reducesdensity of the gas as the plasma is formed, which increases its volumeand velocity) within the plasma plenum 80 to generate a plasma streamvia a plasma arc created between the electrode 60 and the nozzle 100.

Experimental studies have indicated that nozzle temperature during theuse (e.g., and the extent to which a nozzle can be kept cool) can have asignificant impact on electrode life. In particular, as a result of therelatively high operating temperature in high current air-cooled plasmaarc cutting that can significantly increase the material wear anderosion, electrode and nozzle life can be low relative to lower currentair-cooled plasma arc cutting systems. Accordingly, increased coolingcan be a useful technique in extending or prolonging the usable lifespan of an electrode and/or an air-cooled nozzle. Cooling can beachieved by directing gas (e.g., air, nitrogen or oxygen) through theelectrode and/or nozzle surfaces. The flow of gas through these elements(e.g., electrode or nozzle) can be directed along internal and/orexternal surfaces. In some cases, the plasma arc torch can be an aircooled torch that is cooled by directing one or more high speed coolinggas flows (e.g., air at about 20 standard cubic feet per hour (scfh) toabout 250 scfh) through various channels defined within the torch tip.

Some embodiments described herein can increase (e.g., significantlyenhance) the cooling of the torch consumables (i.e., even without theuse of cooling liquids), such as a torch nozzle, thereby improving theusable life span. In some embodiments, nozzle cooling can beaccomplished by utilizing shield flow and allowing the shield flow todirectly flow towards one or more surfaces of the nozzle. For example,in some embodiments, the shield flow can be directed such that itimpinges (e.g., flows perpendicularly with respect to) a nozzle surface.

In some aspects, certain consumable components used within the torch(e.g., the nozzle) can include one or more of various features orelements, such as cooling flow channels, to help increase the coolingcapabilities, and therefore increase the performance and usable life, ofthe nozzle.

For example, referring to FIG. 2, in some aspects, a nozzle 200 can beformed from a body 202. In some embodiments, the body 202 is formed of ametal material, such as copper. As illustrated, the body 202 can be inthe form of a hollow substantially cylindrical body that has a first end204 and a second end 206 that define a longitudinal axis 208. The hollowbody defines a hollow plenum region 201 configured to receive andaccommodate an electrode and to direct a plasma gas between theelectrode and the nozzle. The first end 204 is typically formed andconfigured to mate with one or more features or components of the torch.For example, in some embodiments, the nozzle can be configured to mateagainst a swirl ring or a retaining cap arranged within the torch. Thecylindrical body also includes a generally annularly formed cylindricalwall (e.g., a plenum side wall) 210 that extends upward from a basestructure (e.g., a plenum floor) 212 defined at the second end 206. Thesecond end 206 typically defines a generally cylindrical bore (e.g., aflow conduit) 214 formed generally axially through the plenum floor.During use, plasma gas passes through the bore 214 and out of the nozzlethrough an exit orifice 215. The nozzle exit orifice 215 is defined atthe distal end of the bore 214 along a nozzle end face formed along thesecond end 206.

For cooling, as well as flow distribution, a gas channel (e.g., acooling gas flow channel) 216 can be formed at the first end 204 withina portion of the body, such as the plenum side wall, in particular,between an interior wall 218 and an exterior wall 220 to direct gas flowaround the cylindrical body. For example, the gas channel 216 can be asubstantially annular (e.g., circular) channel disposed in-between theinterior wall 218 and exterior wall 220 to direct the gas flowcircumferentially about at least a portion of the body. As discussedabove, in some cases, the interior wall 218 and/or the exterior wall 220can be configured to interface and mate with other components, such as aswirl ring, disposed within the torch to properly position and mount thenozzle or to direct gas flow to or within the flow channel. Therefore,in some cases, the swirl ring can be configured to form a portion (e.g.,an upper portion) of the gas channel 216 along with the interior walland exterior wall, essentially forming a flow conduit about the nozzle.

The configuration of the nozzle walls relative to the other componentswithin the torch typically helps to separate and seal the flow channelfrom some of the other gas channels within the torch. For example, thenozzle is typically configured to isolate the shield/cooling gas flowingwithin the flow channel from plasma gas flowing within the plenumregion. However, the plasma gas and the shield/cooling gases typicallycombine when they exit the torch (i.e., at the exit orifice of thenozzle).

The nozzle 200 includes one or more inlet passages 222 and one or moreoutlet passages 224 fluidly connected to the gas channel 216 to providegas to and from the gas channel. The inlet passages and the outletpassages can be in the form of any of various structurally suitablefeatures configured to contain and deliver gas to and from the gaschannel. For example, the passages can be a hole, a channel, a tube, aconduit, a duct, or similar features arranged in or on the nozzle body.As discussed below, the passages can also include one or more ports(e.g., openings) formed along different surfaces of the nozzle throughwhich gas can enter and exit the nozzle body to be delivered to and fromthe gas channel.

The inlet passages are typically formed substantially perpendicularlyrelative to at least one surface of the gas flow channel so that the gasthat is expelled from the inlet passage into the flow channel impingesthe nozzle surfaces within the channel to generate turbulent flow withinthe flow channel. Such impinging and turbulent flows generated thereinare expected to increase nozzle cooling performance. To achieve thisarrangement of the inlet passage relative to the flow channel, manydifferent configurations are possible. For example, as illustrated, theinlet passages 222 can be formed through the exterior wall 220 and, wheninstalled in the torch, can be in fluid communication with the shieldgas supply of the torch. As illustrated, the inlet passages 222 can bearranged horizontally (i.e., horizontally relative to a torch that ispositioned so that its longitudinal axis is vertical) so that gasentering the flow channel can strike an inner wall on an opposingsurface of the flow channel (e.g., an outer surface of the interior wall218). In some examples, the term opposing surface refers to a region ofthe flow channel that is generally across from the inlet passage withrespect to a central region of the flow channel. In some embodiments,the inlet passages 222 can be arranged radially in the nozzle (i.e.,extending inwardly towards its central, longitudinal axis 208).

The nozzle can include multiple inlet passages 222, for example, threeinlet passages 222 in the embodiment illustrated in FIG. 2. As shown, insome embodiments, the inlet passages 222 can be arranged substantiallyuniformly (e.g., evenly separated) around the gas channel 216. Forexample, when three inlet passages are included, they can be separatedfrom one another by about 120 degrees. In some cases, a more uniformdistribution of inlet passages 222 can create a more even cooling gasflow into the gas channel 216.

In some embodiments, one or more inlet passages include an inlet portdefined along a radial surface of the body that exposes the inletpassage to the environment surrounding the nozzle. During use, gas(e.g., shield gas or cooling gas) can enter the inlet passage throughthe inlet port and travel on to the gas channel. For example, asillustrated, an inlet port 223 can be in the form of hole defined alongan outer surface of the exterior wall 220 of the nozzle.

The outlet passages 224 are typically formed at least partially throughthe plenum side wall 210 to deliver gas flow away from the gas channel.In some cases, arranging the outlet passages 224 through the plenum sidewall 210 can also help cool the nozzle by creating additional heattransfer surface area within the plenum side wall. As illustrated, theoutlet passage 224 can be formed longitudinally (e.g., at leastsubstantially aligned with (e.g., substantially parallel to) thelongitudinal axis 208).

The outlet passages are also typically formed substantiallyperpendicularly relative to at least one exterior surface of the nozzle(or another consumable component) so that the gas that is expelled fromthe outlet passage impinges against the exterior nozzle surfaces tofurther cool the nozzle. In some embodiments, outlet passages 224 can beformed within (e.g., longitudinally within) the plenum side wall 210 sothat it is proximate to a recess or flange defined along the outersurface of the nozzle against which gas from the flow channel cancontact (e.g., impinge) for better cooling. For example, as illustrated,the outlet passages 224 can be arranged vertically (e.g., substantiallylongitudinally) so that gas exiting the flow channel can strike an outersurface of the nozzle (e.g., a flow impingement surface) 252. That is,in some embodiments, the outlet passages 224 can be arrangedsubstantially parallel to the longitudinal axis (e.g., be longitudinallyoriented).

The nozzle typically includes multiple outlet passages 224, for example,three outlet passages in the embodiment illustrated in FIG. 2. As shown,in some embodiments, the outlet passages 224 can be arrangedsubstantially uniformly around the gas channel 216. For example, whenthree outlet passages are included, they can be separated from oneanother by about 120 degrees. In some cases, a more uniform distributionof outlet passages 224 can create a more even flow of gas from the gaschannel 216. This can be achieved by using additional outlet passages,e.g., four (or more) outlet passages oriented at 90 degrees from eachother (not shown).

In some embodiments, the outlet passage includes an outlet port formedthrough a radial and/or an axial surface of the body between the secondend (e.g., distal end) 206 of the nozzle and the inlet port, where theinlet port connects the inlet channel to the environment surrounding thenozzle and the outlet port similarly connects the outlet channel to theenvironment surrounding the nozzle. For example, gas can flow from thegas channel 216, into the outlet passage 224 formed within the plenumside wall, and out of the plenum side wall through an outlet port 225defined within an outer surface of the plenum side wall.

In some embodiments, the inlet passages 222 and the outlet passages 224are offset (e.g., radially offset) from one another around the flowchannel. For example, the inlet passages and the outlet passages can besubstantially evenly, circumferentially offset from one another. Thatis, in some cases, one or more of the outlet passages 224 can bearranged between (e.g., equidistantly between) two of the inlet passages222 (e.g., at 60 degree intervals in embodiments having three inletpassages and three outlet passages). Briefly referring to FIG. 7, whichillustrates a simulated gas flow through the inlet passages 222, the gaschannel 216, and onto the outlet passages 224, such an arrangement canincrease exposure between the fluid and nozzle, and help increase fluidmixing within the gas channel 216 by providing a longer distance thatthe gas typically travels within the gas channel between an inletpassage and an adjacent outlet passage. Based at least in part on theincreased mixing, the flow can be directed so that gas in the flowchannel can flow circumferentially around the body. In some cases, theflow can be directed circumferentially all of the way around (e.g., atleast 360 degrees around) the flow channel. Also illustrated in FIG. 7,the flow velocities through the inlet passages 222 and the outletpassages 224 are typically higher than the gas flow elsewhere around thegas channel 216. Further, the increased flow velocities through theinlet passages 222 can help to create the turbulent gas flow and coolingas air exits the inlet passage 222 and impinges upon an inner surface ofthe gas channel 216.

In some embodiments, the cooling gas passageways (e.g., the inletpassages 222 and primarily the outlet passages 224) are sized andconfigured to permit the nozzle to operate in the plasma arc torch at acurrent flow of at least 75 amps (e.g., at least 100 amps).Additionally, in some embodiments, the cooling gas passageways are sizedand configured to permit operation of the nozzle at a current to nozzlebody length ratio of greater than 150 amps per inch (e.g., greater than170 amps per inch).

Such current flow can help to cut materials at faster cutting speeds.For example, in some cases, the torch can cut half inch mild steel at acutting speed that is greater than 100 inches per minute (ipm).

While the inlet passages and the outlet passages have been described asgenerally being multiple discrete round holes, other configurations arepossible. For example, in some embodiments, a nozzle can include justone inlet passage and one outlet passage to deliver gas to and from theflow channel. Alternatively, in some cases, the inlet passage and/or theoutlet passage can be in the form of one or more substantially annular(e.g., partially or fully annular) openings formed around the nozzlebody.

Torch systems can additionally or alternatively include other types ofconsumable cooling systems, such as nozzle cooling systems or nozzle andshield cooling systems, arranged at one or more regions within thetorch. For example, consumable cooling systems can include featuresformed in or on one or more consumables (e.g., a nozzle, shield, and/ora retaining cap for the nozzle or the shield) to receive and direct gasflow (e.g., high speed cooling gas flow) to increase cooling of one ormore of the consumables and cutting performance of the torch.

For example, referring to FIG. 3, in some aspects, a torch 300 caninclude a nozzle cooling system 310 and/or a nozzle and shield coolingsystem 320, which can each be implemented alone or in combination withone another to cool the components of the torch.

In some embodiments, to increase air cooling performance of the torch300, the nozzle cooling system 310 can include a torch retaining cap 330having features configured to direct cooling gas flow towards gasreceiving surfaces of a nozzle 350. In particular, the retaining cap 330is typically formed of a generally cylindrical body 332 having asecuring flange 334 to retain the nozzle 350 within the torch. At an endtypically opposite the securing flange 334, the retaining cap 330typically includes a connection region (e.g., a threaded connection) 335to secure the retaining cap 330 (and therefore also the nozzle 350) tothe torch body.

As discussed in detail below, the securing flange 334 defines one ormore gas holes or openings (e.g., gas supply ports) 336 that permit gasto flow through the retaining cap and on to the nozzle 350 for cooling.As illustrated, the gas supply ports 336 are typically arrangedgenerally longitudinally with respect to the retaining cap and torch.Also, the gas supply ports 336 are positioned within the securing flange334 generally substantially perpendicularly relative to a gas receivingsurface (e.g., an impingement surface) 352 of the nozzle 350. Forexample, in some embodiments, the gas supply ports 336 are angled (e.g.,arranged or directed inwardly towards the nozzle or longitudinal axis)relative to the longitudinal axis to direct cooling gas flow against theimpingement surface 352.

The retaining cap typically includes multiple supply ports 336 (e.g.,ten in the example shown in FIG. 3) arranged around the securing flange334. In some embodiments, the supply ports 336 can be arrangedsubstantially uniformly around the securing flange 334 to deliver gassubstantially uniformly to the nozzle. For example, when ten supplyports are included, they can be separated from one another by about 36degrees. In some cases, a more uniform distribution of supply ports 336can create a more even flow of gas from the shield gas supply.

As mentioned above, the nozzle 350 includes an exterior feature (e.g., arecess) 354 defined along its outer surface to receive and redirect acooling gas flow (e.g., the high velocity gas flow received from theretaining cap 330) to increase cooling capabilities. For example, asillustrated, the feature 354 can define the cooling gas receivingsurface (e.g., the impingement surface) 352 that is positionedsubstantially perpendicularly relative to the longitudinal axes of thevarious gas supply ports 336. As discussed above, the substantiallyperpendicular positioning of the impingement surface 352 relative to thegas supply port(s) 336 helps to increase cooling capabilities at leastin part by generating turbulent gas flows. In some cases, the gas flowthrough the supply ports 336 towards the impingement surface 352 isdelivered at about 200 scfh (e.g., at speed of about 66986 feet perminute).

While the impingement surface 352 has been described and illustrated asgenerally being in the form of a surface defined within a recess, otherconfigurations are possible. For example, in some embodiments, a nozzlecan define an impingement surface that extends from its outer surface(e.g., along a flange) rather than being formed within a recess alongthe nozzle body. Additionally, in some cases, the impingement surfacecan be an outer surface of the nozzle that has a substantially similarshape and profile as the rest of the outer surface of the nozzle. Thatis, in some cases, the nozzle may be configured to receive a coolingflow along its outer surface without having additional, substantiallymodified features (e.g., impingement surface 352, feature 354, etc.) toreceive the cooling gas flow.

While certain features or aspects of the nozzle 350 have been describedwith respect to the example in FIG. 3, it is noted that some otherfeatures of the nozzle 350 that are not inconsistent with or affected bythe cooling system described above can be substantially similar to thoseof the of the nozzle 200 described above.

Alternatively or in combination with the nozzle cooling system 310, thetorch can also include a nozzle-shield cooling system 320 to help cool ashield 380 disposed at the tip of the torch 300 to protect the nozzlefrom molten material (e.g., spatter) ejected from a workpiece. Forexample, in some embodiments, the nozzle-shield cooling system 320includes a recess or profile (e.g., a mixing channel) 322 defined withinthe shield 360 and/or the nozzle 350 that is used to direct andcirculate cooling gas flow between the shield 360 and the nozzle 350. Asillustrated, the mixing channel 322 can be defined in close proximity toone or more components of the nozzle cooling system 310 (e.g., near thefeature 354 or the impingement surface 352). In some cases, the mixingchannel 322 is shaped having a substantially curved profile (e.g., abulbous profile) to encourage a circulating flow therewithin.

In such a configuration, during use, cooling gas flow can be deflectedaway from the nozzle 350, for example, in part as a result of theangular arrangement of the impingement surface 352, and into the mixingchannel 322 to be circulated. As noted above, the turbulent mixing flowgenerated by gas being deflected from the impingement surface 352 (orother flow deflecting surfaces of the nozzle of shield) into the mixingchannel can increase the cooling capabilities of the nozzle-shieldcooling system 320 and/or the nozzle cooling system 310.

The mixing channel 322 is typically partially formed by an edge (e.g.,an inlet edge (e.g., a sharp inlet edge)) 324 defined along a surface ofthe shield 360 to capture a cooling gas flow and redirect the flow, forexample from the impingement surface 352, into the mixing channel 322for circulation and cooling. The edge 324 is typically formed to captureand re-direct the cooling gas flow flowing towards the torch tip intothe mixing channel 322. For example, the edge 324 can include a sharpedge (e.g., defined by two surfaces positioned at an acute anglerelative to one another) that is pointed away from the torch tip tointercept the cooling gas flow.

Alternatively or additionally, in some embodiments, the mixing channel322 can be partially formed by an edge (e.g., an inlet edge (e.g., asharp inlet edge)) 324A defined along a surface of the nozzle 350 (i.e.,an edge between the impingement surface 352 and the vertical(longitudinal) surface extending from the impingement surface 352) tocapture a cooling gas flow from the supply ports 336 and redirect theflow outwardly towards the mixing channel 322.

The mixing channel 322, and in some cases also the mixing channel edge324, typically extend at least partially around nozzle. In some cases,the mixing channel 322 and edge 324 are defined within an interiorsurface of the shield and extend fully around an interior surface of theshield 360. In some cases, the mixing edge 324A is defined within anexternal surface of the nozzle 350 and extends fully around an externalsurface of the nozzle 350.

In some embodiments, the shield can include additional features (e.g.,edges) to direct flow. For example, the shield can include multipleedges to direct flow within the mixing channel. These edges can beoriented upwardly (e.g., 324) or downwardly (not shown). Additionally oralternatively, the shield can include additional edges to direct flowinto additional flow channels (e.g., additional cooling orflow-directing channels) formed within the shield.

While the cooling systems (e.g., the nozzle cooling system 310 and thenozzle-shield cooling system 320) described above have been described asprimarily providing beneficial cooling properties, other advantageousperformance capabilities can be obtained by their implementation. Forexample, in addition or as an alternative to the increased coolingcapabilities discussed above, the features defined on the shield and/orthe nozzle can increase gas flow properties so that a more uniform andevenly distributed flow of shield gas can be delivered to the torch tip.That is, in some cases, the features (e.g., the mixing channel or theimpingement surface) can act as one or more flow distribution (e.g.,flow buffering) chambers to smooth the flow transients. As discussedabove, such evenly distributed flow can increase material processingperformance by helping to create a more stable plasma arc.

Additionally, while certain features have been described above as beingincluded on particular components, such as the mixing channel 322 beingdefined along an interior surface of the shield 360, otherconfigurations are possible. For example, in some cases the mixingchannel can be formed within an exterior surface of the nozzle.Alternatively, the mixing channel can be formed partially in both thenozzle and the shield, whereby the partial mixing channels direct flowbetween the two partial mixing channels to achieve the desired coolingand flow distribution properties.

Referring to FIG. 4, in some aspects, a torch can include a nozzledefining the gas channel 216 as discussed above with respect to FIG. 2,as well as the nozzle cooling system 310 and/or the nozzle-shieldcooling system 320 discussed above with respect to FIG. 3. In somecases, the shield gas provided by the torch body can be distributed anddirected to one or more of the various channels and passages arranged tocool the shield and the nozzle. As illustrated and indicated usingarrows in FIG. 4, a gas flow (e.g., a cooling/shield gas flow) 101 canfirst be delivered near the retaining cap securing flange. Upon reachingthe securing flange 334 of the retaining cap and the exterior wall 220of the nozzle, the gas flow can be divided and distributed between thenozzle inlet passage 222 and the gas port 336 formed through thesecuring flange. Alternatively, in embodiments where the torch does notinclude either of the nozzle with a cooling flow gas channel 216 or anozzle cooling system 310 or nozzle-shield cooling system 320, the gasflow 101 can instead be directed only into one of the subsequent flowpassages based on the various components present in the torch (e.g.,directed only to the gas port 336 or only to the inlet passage 222).

A first flow portion 101A directed into the one or more inlet passages222 through the inlet port 223, as discussed above, can be directed intothe gas channel 216. The gas flow can be circulated within the gaschannel 216 for mixing and cooling the nozzle and then subsequently tothe one or more outlet passages 224 (shown in phantom) for distributionand cooling of the nozzle 350. The flow 101A can be expelled from theoutlet passage 224, for example at the outlet port 225, so that it cancontinue between the nozzle 350 and the shield 360 to be expelled asshield gas between the shield and nozzle, and surrounding the plasmaarc.

A second flow portion 101B, which flows into the one or more gas ports336, can be directed (e.g., at high speed) towards the nozzle to coolthe nozzle. As discussed above, the gas flow can be directed to theimpingement surface 352 along the outer surface of the nozzle. Thesecond flow portion 101B can strike the impingement surface 352 at asubstantially perpendicular angle to create a turbulent flow behaviorand increase cooling. Additionally or alternatively, the first flowportion 101A expelled from the outlet port 225 can also impinge upon theimpingement surface 352 for cooling and to help generate turbulent flow.

After being deflected from the impingement surface 352, gas flow (e.g.,the first flow portion 101A and/or the second flow portion 101B) canflow outwardly and into the mixing channel 322 to circulate and helpcool the shield and to be mixed and distributed circumferentially withinthe mixing channel 322. As mentioned above, in some cases, the edge 324can help to intercept gas flow and direct it into the mixing channel322. After mixing and creating turbulent flow within the mixing channel322, gas is directed into the annular passage (e.g., the shield gas flowpassage) 175 arranged between the nozzle 350 and the shield 360 to beexpelled from the torch tip.

The arrows illustrated to denote gas flows within the passages (e.g.,the first flow portion 101A and the second flow portion 101B) are merelyused to show simplified example flow patterns. It is noted that theactual gas flow pattern within the flow passages, in particular withinthe mixing channel, typically has turbulent flow and is highly erratic.Therefore, the actual flow within the passages may be different from theexample arrows illustrated.

While FIG. 4 illustrates a torch having multiple consumable componentcooling features and systems together in combination, otherconfigurations are possible.

That is, for example, in some aspects, a torch may include the gaschannel 216 disposed within the nozzle along with related passages andflow directing features that work in combination with the gas channel216 to cool the nozzle. However, the torch may omit one or more of theother component cooling systems described herein (e.g., the nozzlecooling system 310 and/or the nozzle-shield cooling system 320).Similarly, in some aspects, a torch may include one or more of thecomponent cooling systems described herein that utilize features andflow paths defined in the shield, nozzle, and or retaining cap (e.g.,the nozzle cooling system 310 and/or the nozzle-shield cooling system320), but the torch may include a nozzle that does not have the gaschannel 216 and related flow passages.

In addition or alternatively to the various component cooling systemsand aspects described above, torches described herein can includeconsumable components that include features or elements that can beimplemented to provide a more uniform flow of shield gas emitted fromthe torch tip. Since the presence of vent holes in the shield (e.g.,vent holes 362 illustrated in FIGS. 3 and 5) can cause shield gas flownon-uniformities, locating features for enhancing flow uniformitybetween the shield vent holes and the shield exit orifice can result inincreases in gas flow uniformity about the plasma exiting the shield,thereby producing improved cutting performance and resulting in reducedwear of torch consumables.

For example, referring back to FIG. 3, the torch 300 can also include ashield gas flow distribution system 380, which can include one or morefeatures of the nozzle 350 and the shield 360 that work in combinationwith one another to distribute flow about the substantiallycircumferential shield gas flow channel 175. For example, the flowdistribution system 380 can define an alternating flow channel thatdirects or disrupts the flow of the shield gas in an alternating (e.g.,zig-zag, S-shaped, or tortured flow path) manner to create a turbulentflow and distribute flow circumferentially around the nozzle. Asdiscussed above, a more evenly distributed flow of the shield gas can behelpful to generate a more stable plasma arc for better cuttingperformance.

In particular, in some embodiments, the flow distribution system 380 canbe formed by a flow directing feature 382 extending from the shield(e.g., from the interior surface of the shield) to alter (e.g., disturb,re-direct, or reverse) the flow of shield gas passing through the shieldgas passage 175. The flow directing feature 382 can be configured towork in combination with a complementary flow receiving feature 390defined within the outer surface of the nozzle to form an altered,reversed shield gas flow path 175A within a mixing region (e.g., arecombination region) 396 defined within the flow distribution system380. Flow reversal of at least a portion of the shield gas passingthrough the shield gas flow distribution system 380 is desirable.

Referring to FIGS. 3 and 5, the flow directing feature 382 can includeany of various physical elements that are structurally suitable topartially obstruct (e.g., direct, re-direct, reverse, or otherwisealter) the flow of the shield gas flowing through the shield gas channel175. For example, the flow directing feature 382 can be in the form of aprotuberance (e.g., a flange, a baffle, a projection, a sharp bump, aprotrusion, or another suitable physical element) 383 extending awayfrom the interior surface of the shield 360. In some embodiments, theflow directing feature 382 can form a tortured flow path. Typically, asillustrated in FIGS. 3 and 5, the flow directing feature 382 extendsfrom the shield 360 in a direction that is inconsistent (e.g., opposing)the general flow of the shield gas flow channel 175 towards the torchtip. For example, in some embodiments, the protuberance 383 can extendtowards a proximal end of the torch (e.g., away from the torch tip).That is, the protuberance 383 can be directed in the opposite directionthat the shield gas and plasma gas generally travel during use.

For example, referring more particularly to FIG. 5, the flow directingfeature can be positioned so that as gas flows through the shield gasflow channel and strikes the flow directing feature 382, the gastypically makes contact with an impingement surface 384 formed where theflow directing member (e.g., the protuberance) extends outwardly awayfrom the interior surface of the shield. As a result of thisconfiguration, the flow directing feature 382 (e.g., the protuberance383) disturbs the flow of shield gas and temporarily directs it upwardlyand into the nozzle (e.g., the flow receiving feature 390).

The various elements of the flow directing feature 382 (e.g., theprotuberance 383 or the impingement surface 384) can each be formedcontinuously or in one or more segments substantially circumferentiallyaround the shield 360. In some embodiments, the flow directing feature382 may have a substantially uniform height about the shield.

The flow receiving feature 390 typically includes one or more elementsthat fit complementary with the elements of the flow directing feature382 (e.g., the protuberance 383 and/or the impingement surface 384) todirect the flow of shield gas to the nozzle and shield and to evenlydistribute shield gas evenly around the bore 314. As illustrated in FIG.5, in some embodiments, the flow receiving feature 390 includes aportion (e.g., a flow feature, such as a ridge, a flange, a baffle, aprojection, a sharp bump, a protrusion, or another suitable physicalelement) 392 that extends outwardly away from the exterior surface ofthe nozzle to direct shield gas flow. For example, the ridge 392 candirect shield gas flow outwardly towards the shield. In particular, theridge 392 can be complementarily positioned to direct shield gas flowinto the impingement surface 384 of the shield. While certainconfigurations have been described and illustrated, other configurationsare possible. For example, as depicted in FIG. 5A, some or all of thefeatures described as being disposed along the nozzle (e.g., the flowreceiving feature 390) may be alternatively disposed along a surface ofthe shield and some or all of the features described as being disposedalong the shield (e.g., the flow directing feature 382) canalternatively be disposed along a surface of the nozzle.

Additionally or alternatively, the nozzle 350 can also include a nozzleflow receiving feature (e.g., a recess or groove) 394 to receive andre-direct a flow of gas that is directed proximally away from the torchtip by the shield impingement surface 384 and the protuberance 383. Inparticular, the recess 394 can be formed within the outer surface of thenozzle and define a nozzle impingement surface 398 to receive andre-direct the flow of shield gas.

The various elements of the flow receiving feature 390 (e.g., theprotuberance 392, the recess 394, or the impingement surface 398) caneach be formed continuously or in one or more segments substantiallycircumferentially around the nozzle 350.

During use of the torch, shield gas flow 101 is typically directedtowards the torch tip in the shield gas flow channel 175 formedannularly between the nozzle 350 and the shield 360. In some cases, theshield gas flow 101 flows inconsistently circumferentially around theannular shield gas flow channel 175, for example, as a result of theflow being provided through one or more discrete flow channels (e.g.,the ports 336) formed around the nozzle 350. To help alleviateinconsistencies, flow 101 can be directed into the shield impingementsurface 384 and the protuberance 383, which deflect and re-direct theflow upward (i.e., away from the shield bore 314) and into the nozzlerecess 394 and the nozzle impingement surface 398. In some cases, thenozzle protuberance 392 helps to capture some or all of the flow thatimpinges the shield impingement surface 384 to help limit the shield gasflow 101 from inadvertently traveling upstream within the shield gasflow channel 175. Rather, the nozzle protuberance 392 can help to directflow to continue downstream (e.g., into the nozzle recess 394) andtowards the shield bore 314.

Directing the shield gas flow 101 upward into the recess 394 (e.g., andinto the mixing region 396 defined therein) can have one or more effectson the flow. The features along the nozzle and the shield that definethe mixing region 396 can also help to distribute the shield gas moreevenly within the shield gas flow channel 175 circumferentially aroundthe bore 314. For example, the flow 101 can impinge the shieldimpingement surface 384 and protuberance 383 and be directed upwardly,the flow 101 can fill the nozzle recess 394 and be distributed annularly(e.g., can flow circumferentially) therewithin. As the recess 394 andthe mixing channel 396 fill with shield gas flow 101, the more evenlydistributed flow can then be directed by the nozzle impingement surface398 downstream and out of the shield gas flow channel 175 through theshield bore 314 to surround a plasma arc. In some cases, the shield gasflow exiting the mixing channel is substantially uniformly distributedannularly around the nozzle.

The flow distribution system 380 is typically arranged near the distalend (e.g., the tip of the torch) close to the shield's bore (e.g., exitorifice) 314 to distribute the gas flow around the shield to help createa more uniform flow of shield gas leaving the shield bore 314. To helplimit the influence of the other flow features of the shield or thenozzle, the flow distribution system 380 is typically arranged closer tothe shield bore 314 than most (e.g., all) of the other flow alteringfeatures. For example, in some embodiments, the flow distribution system380 (i.e., and therefore the related features on the shield and thenozzle associated with the flow distribution system 380) is typicallyarranged between the shield bore 314 and shield vent ports (e.g.,metering holes) 362 to limit inconsistent flow that could be caused bygas escaping the shield gas flow channel 175 through the vent ports 362.Additionally, in embodiments where the torch also includes a mixingchannel 322, the mixing region 396 is typically arranged between theshield's bore (e.g., exit orifice) 314 and the mixing channel 322.

While the features described above with respect to FIG. 5 have primarilybeen described as providing flow distribution to create a more uniformflow, the features may also provide increased cooling capabilities. Forexample, gas flow into the recess feature on the outer surface of thenozzle, as directed by the flow feature extending from the interiorsurface of the shield, can cool the nozzle, at least in part as resultof circulating, turbulent flow generated within the recess feature.

In other aspects, nozzles used within torches can be sized,proportioned, and configured to have increased cooling capabilitieseither alone or in combination with any of the cooling systems ortechniques discussed herein. In particular, nozzles can be designed,proportioned, and constructed to have an increased tip mass to volumeratio relative to the rest of the nozzle. That is, the nozzle can have ahigher concentration of mass located at its distal tip (e.g.,surrounding or near the bore), which can help promote conductive coolingof the nozzle for air-cooled torch embodiments. In particular, increasedmaterial mass at the distal tip or the nozzle, especially increasedmaterial extending radially away from the longitudinal axis can providegreater heat transfer paths through which heat can travel outwardlywithin the nozzle and away from the torch tip. The additional heatconduction flow area is required to prevent premature failure ofair-cooled torches for high current (e.g., greater than 100 Amp)torches, increase consumable or cutting life and to maintain high cutquality at high speed, which can be enabled based on the better coolingcharacteristics.

For example, in some embodiments, a nozzle can have a longitudinallyshorter proximal end height, a wider nozzle tip (e.g., a larger endface), thicker plenum side walls, and/or have a longer bore (i.e., athicker plenum floor) that can produce greater cooling effects byproviding increased mass through which heat can travel for cooling.

In some embodiments, referring to FIG. 6, a nozzle 500 for a gas-cooledplasma arc torch typically includes a body (e.g., a generally hollowcylindrical body) 502. In some embodiments, the body 502 is formed of ametal material, such as copper. The body 502 has a first, proximal end504 and a second, distal end 506, and a longitudinal axis 508 thatextends substantially centrally through the cylindrical body 502. Thebody 502 is typically formed of a generally annular cylindrical wall(e.g., a plenum side wall) 510 that extends upwardly from a basestructure 512 defined at the second end 506. The plenum side wall 510defines an opening to accommodate an electrode when assembled into atorch. The width (e.g., the radial width) of the plenum side wall isreferred to herein as the plenum side wall thickness 511.

The base structure 512 typically defines a bore (e.g., a cylindricalhole or a conduit) 509 centrally formed between a plenum floor 516 and anozzle end face 518 disposed along the distal end 506. In someembodiments, the plenum floor 516 is located along a surface or featureproximate where an electrode contacts the nozzle to start a plasma arc(e.g., a contact start region). The bore 509 typically has a width(e.g., diameter) 509A and a length (e.g., a conduit length) 509B, andextends through the end face 518 via an opening (e.g., a central nozzleexit orifice) 514. As illustrated, in some embodiments, the bore 509 caninclude a surface modification along one or more of its cornersincluding a counterbore, a chamfer, a frusto-conical region and/or afillet at each end of its length (e.g., at its proximal and/or distalend). In some cases, the bore 509 has a chamfer or a counter bore ateach end. Additionally or alternatively, the width of the bore 509 canvary along its length or even have a non-uniform shape along its length.

The distance between the plenum floor 516 and the end face 518 isreferred to herein as the plenum floor thickness (e.g., a distal portionlength) 517. The bore length 509B typically corresponds (e.g., can beequal) to the plenum floor thickness 517. In some cases, surfacemodifications, such as counterbores, angled features, chamfers, orfillets can be included in the plenum floor thickness 517. The distancebetween the plenum floor 516 and the proximal end 504 is referred toherein as a proximal end length 515. During use, plasma gas can flowthrough the bore and be expelled from the nozzle at the exit orifice514.

The proximal end 504 is typically formed and configured to mate with oneor more features or components of the torch. For example, in someembodiments, the nozzle proximal end 504 can be configured to mateagainst a swirl ring arranged within the torch.

In some embodiments, the nozzle has a nozzle body length 520 that isdefined by its nozzle portion (i.e., exclusive of a flange portion thatmay be included as illustrated in FIG. 6) and a nozzle width 522 in adirection that is perpendicular (e.g., transverse) to the longitudinalaxis and length. That is, the nozzle length 520 can include the proximalend length 515 and the distal portion length 517, but not the lengthassociate with additional flanges that may be arranged for mounting thenozzle (e.g., a nozzle body flange 530 discussed below).

The nozzle can also include the body flange 530 at the proximal end,which can be used for positioning the nozzle or for implementing variouscooling features and techniques. In some embodiments, the proximal endlength 515A includes the distance between the plenum floor 516 and theend of the nozzle including the flange 530. As such, an overall nozzlebody length 524 can be defined by a distance from a proximal end of thenozzle body flange 530 to the end face 518. In some embodiments, thenozzle can be designed such that the overall nozzle body length 524 ofthe nozzle is greater than the nozzle body length 520. In someembodiments, the body flange (e.g., flange 530) can extend above thenozzle plenum. In some embodiment, the body flange (e.g., flange 530)can extend a small percentage (e.g., about 5 percent to about 40percent) above the nozzle plenum. In some embodiments, the body flange(e.g., flange 530) can extend about 0.05 to about 0.5 inches above thenozzle plenum.

As discussed above, the nozzle can have certain dimensions andproportions that are designed and expected to produce increased coolingcapabilities. For example, the nozzle body typically has a nozzle bodylength 520 that is greater than its nozzle body width 522 and where aratio of the proximal end length 515A to the plenum floor thickness 517is less than about 2 (e.g., less than about 1.4). In some embodiments, aratio of a length of the second, proximal portion 504 (e.g., at leastpartially defined by the proximal end length 515A) to the conduit length509B is less than about 2 (e.g., less than about 1.4). Such proportionsare expected to permit greater amounts of heat to transfer throughnozzle, for example, outwardly (e.g., away from the bore 509) andupwardly (e.g., away from its end face 518).

Other plasma torch nozzles, for example, nozzles previously manufacturedby Hypertherm of Hanover, N.H. have been sized and proportioned suchthat their ratios of proximal end length to plenum floor thickness (orbore length) were greater than 2. For example, one such nozzle (i.e., a40 Amp nozzle identified by part number 2-014) has a proximal end lengthto bore length ratio that is about 2.98. Similarly, another nozzle(i.e., a 0.059 nozzle identified by part number 3-007) has a proximalend length to bore length ratio that is about 2.44.

In some embodiments, a ratio of the length of the bore 509B to thenozzle body length 524 is greater than about 0.25 (e.g., greater than0.30, greater than 0.32, or greater than 0.35). Nozzles having suchproportions in which the length of the bore (e.g., 509B), and thereforein some cases the thickness of the distal portion length, is relativelylarge when compared to the nozzle body length (e.g., nozzle body length520 or the nozzle body length 524) can have increased mass concentratedat the distal end, which can help to increase cooling. That is, theincreased amount of material arranged at the distal end is expected toprovide greater thermal conductivity through which heat can transferaway from the tip for cooling.

In some embodiments, a nozzle for which a ratio of the conduit length(e.g., bore length) 509B to nozzle body length 524 is greater than about0.25 (e.g., greater than 0.30, greater than 0.32, or greater than 0.35)can also be configured to permit operation at a current to nozzle bodylength 524 ratio of greater than about 170 amps per inch.

Other plasma torch nozzles, for example, nozzles previously manufacturedby Hypertherm of Hanover, N.H. have been sized and proportioned suchthat their ratios of conduit (or bore) length to nozzle body length wereat the lower end of the range. For example, one such nozzle (i.e., the40 Amp nozzle identified by part number 2-014, referenced above) has aconduit (or bore) length to nozzle body length ratio that is about 0.25.Similarly, another nozzle (i.e., the 0.059 nozzle identified by partnumber 3-007, referenced above) has a conduit (or bore) length to nozzlebody length ratio that is about 0.29.

The nozzle (e.g., the nozzle 500) can include one or more of thefeatures or elements discussed above with respect to FIGS. 2-5 that canbe implemented to further increase cooling capabilities of the nozzle.For example, in some embodiments, the flange 530 can include a coolingflow channel (e.g., substantially similar to the gas channel 216described above). Additionally, the nozzle (e.g., the flange 530 and/orthe plenum side wall 510) can include the inlet and outlet passages thatto provide gas flow to and from the flow channel as described withrespect to FIG. 2.

In some embodiments, a side wall thickness of the plenum (e.g., theplenum side wall thickness 511) is between an inside diameter of theplenum and an outer diameter of the plenum, and the ratio of the plenumside wall thickness to the width of the nozzle body (e.g., the nozzlebody width 522) is about 0.15 to about 0.19.

While the nozzle 500 has been illustrated and described as having acertain design and features, other configurations are possible. That is,the nozzle can include one or more of the flow features and elements asdescribed above with respect to FIGS. 2-5 without departing from basicdimensions and proportions described herein with respect to FIG. 6 asproviding increased cooling properties

While certain embodiments and configurations of systems and methods havebeen described herein, other configurations are possible. That is, thevarious cooling and flow distribution systems and devices describedincluding the gas channel 216 (and related passages and surfaces), thenozzle cooling system 310, the nozzle-shield cooling system 320, theflow distribution system 380, and the proportioned nozzle 500 havingdimensions as described with respect to the example illustrated in FIG.6 can be implemented within a torch system in any combination of one ormore of these systems and features. In some examples, a torch system mayinclude the gas channel 216 (and related passages and surfaces), thenozzle cooling system 310, the nozzle-shield cooling system 320, theflow distribution system 380, and/or a nozzle having the proportioneddimensions of FIG. 6.

While various embodiments have been described herein, it should beunderstood that they have been presented and described by way of exampleonly, and do not limit the claims presented herewith to any particularconfigurations or structural components. Thus, the breadth and scope ofa preferred embodiment should not be limited by any of theabove-described exemplary structures or embodiments, but should bedefined only in accordance with the following claims and theirequivalents. Other embodiments are within the scope of the followingclaims.

What is claimed:
 1. A nozzle for a gas-cooled plasma arc torch, thenozzle comprising: a hollow generally cylindrical body having a firstend and a second end that define a longitudinal axis, the second end ofthe body defining a nozzle exit orifice; a gas channel formed in thefirst end between an interior wall and an exterior wall of thecylindrical body, the gas channel directing a gas flow circumferentiallyabout at least a portion of the body; an inlet passage formedsubstantially through a radial surface of the exterior wall and fluidlyconnected to the gas channel, the inlet passage defining an inlet portformed through the radial surface of the exterior wall; and an outletpassage at least substantially aligned with the longitudinal axis andfluidly connected to the gas channel, the outlet passage defining anoutlet port formed through a second exterior radial surface of the bodybetween the second end of the nozzle and the inlet port.
 2. The nozzleof claim 1, the nozzle further comprising a plurality of inlet passages.3. The nozzle of claim 2 wherein a radial angle between respective inletpassages is about 120 degrees.
 4. The nozzle of claim 1, the nozzlefurther comprising a plurality of outlet passages.
 5. The nozzle ofclaim 4 wherein a radial angle between respective outlet passages isabout 120 degrees.
 6. The nozzle of claim 1, the nozzle furthercomprising a plurality of inlet passages and a plurality of outletpassages.
 7. The nozzle of claim 6 wherein the inlet passages areradially offset from the outlet passages.
 8. The nozzle of claim 1wherein the circumferential gas flow along the gas channel extends aboutan entire circumference of the nozzle.
 9. The nozzle of claim 1 whereina portion of the nozzle walls are configured to mate with an exteriorsurface of a swirl ring.
 10. The nozzle of claim 9 wherein the swirlring forms a portion of the gas channel.
 11. A nozzle for a gas-cooledplasma arc torch, the nozzle comprising: a hollow generally cylindricalbody having a first end and a second end that define a longitudinalaxis, the second end of the body defining a nozzle exit orifice; aplenum region defined within the body and directing a plasma gas; acooling gas channel formed in the first end between an interior wall andan exterior wall of the cylindrical body, the cooling gas channelisolating a cooling gas from the plasma gas; a substantially radiallyoriented inlet passage fluidly connected to the gas channel, theradially oriented inlet passage defining an inlet port formed through aradial surface of the body; and a substantially longitudinally orientedoutlet passage fluidly connected to the gas channel, the substantiallylongitudinally oriented outlet passage defining an outlet port formedthrough a second radial surface of the body between the second end ofthe nozzle and the inlet port.
 12. The nozzle of claim 11, the nozzlefurther comprising a plurality of radially oriented inlet passages. 13.The nozzle of claim 12 wherein a radial angle between respective inletpassages is about 120 degrees.
 14. The nozzle of claim 11, the nozzlefurther comprising a plurality of outlet passages.
 15. The nozzle ofclaim 14 wherein a radial angle between respective outlet passages isabout 120 degrees.
 16. The nozzle of claim 11, the nozzle furthercomprising a plurality of inlet passages and a plurality of outletpassages.
 17. The nozzle of claim 16 wherein the inlet passages areradially offset from the outlet passages.
 18. The nozzle of claim 11wherein the circumferential gas flow along the gas channel extends aboutan entire circumference of the nozzle.
 19. The nozzle of claim 11wherein a portion of the nozzle walls are configured to mate with anexterior surface of a swirl ring.
 20. The nozzle of claim 19 wherein theswirl ring forms a portion of the gas channel.
 21. The nozzle of claim11 wherein the plasma gas and the cooling gas combine at the exitorifice of the nozzle.
 22. A method for cooling a nozzle for a plasmaarc torch, the method comprising: providing the nozzle having a hollowbody with a first end and a second end, the second end of the bodydefining a nozzle exit orifice, a gas channel formed in the first end ofthe body, a substantially radially oriented inlet passage fluidlyconnected to the gas channel, the radially oriented inlet passagedefining an inlet port formed through a radial surface of the body, anda substantially longitudinally oriented outlet passage fluidly connectedto the gas channel, the substantially longitudinally orientedoutletpassage defining an outlet port formed through a second radial surfaceof the body between the second end of the nozzle and the inlet port;flowing the cooling gas through the inlet passage into the gas channel;directing the cooling gas along the gas channel; and discharging thecooling gas from the gas channel to the outlet passage.